1. Field of the Invention.
The present invention relates to a catcher tube sorter system for a particle flow through apparatus which includes a catcher tube selectively alignable with the flow from the apparatus, and more particularly, concerns a flow cytometer for determining one or more characteristics of particles flowing through the cytometer with such a catcher tube sorter to provide separation of the particles according to the determined characteristics. The method of sorting with a positionable catcher tube is also a part of the present invention.
2. Background Description.
There are a number of cell or particle analyzing devices using flow cytometer equipment and techniques which rely on hydrodynamically focused fluid flow through an analysis orifice where the specific characteristics of the flowing cells or particles can be determined. Flow analysis of particles has been used in the determination of the variety of characteristics of individual particles. This analysis is most useful in determining characteristics of cells for the collection of information which would aid in areas of research, hematology, immunology and the like. The researcher, for example, could be interested in determining specific characteristics of the individual cells where those cells need to be classified, identified, quantified and preferably sorted for further investigations or analysis.
One commercially available flow cytometer which relies on a hydrodynamically focused fluid system is known as the FACScan.TM. instrument sold by Becton Dickinson Immunocytometry Systems, San Jose, Calif. The FACScan.TM. instrument rapidly analyzes cells on the basis of fluorescence and light scatter properties. Analysis is accomplished by introducing cells in suspension to the center of a focused liquid stream thus causing them to pass, one at a time, through a focused light from a high power laser. Each cell is individually characterized by its light scatter signals and by the intensity and color of fluorescence emitted while it is illuminated.
In the aforementioned flow cytometer, a sheath liquid focuses the particles or cells as they pass through the orifice associated with the analyzing or counting capabilities. U.S. Pat. Nos. 4,503,385 and 4,526,276 describe particle analysis systems in which particles flowing in a stream are enveloped in a sheath liquid which focuses and confines the sample liquid (with the particles or cells) to the center of the flowing stream. U.S. Pat. No. 4,110,604 describes a particle density measuring system in which particles flowing in a stream are enveloped in a sheath liquid which focuses and confines the sample fluid (with the particles) to the center of the flowing stream.
In the presently known and available flow through equipment, electrically operated pumps, syringe pumps or the like are used in the fluidics of the system to move the liquid and particle flow through the flowcell analysis orifice and passageways. The usual operation for these pumps is to force or draw liquid with particles from a sample test tube through a sample capillary uptake tube centered in the sheathing liquid flowing in the direction of the particle analysis orifice. The Assignee of the present application has a U.S. Pat. No. 4,790,653, issued Dec. 12, 1988, disclosing a housing for a flow cytometer with a particle unclogging feature; and co-pending applications, U.S. Ser. No. 125,095 filed Nov. 25, 1987 disclosing a sheathed particle flow controlled by differential pressure and U.S. Ser. No. 188,582 filed Apr. 29, 1988 disclosing a backflow isolator and capture system. All of these inventions are useful with the present invention.
"Electronic Separation of Biological Cells by Volume" by M. J. Fulwyler in Science vol. 150, pp. 910-911, November (1965) or "High-Speed Cell Analysis and Sorting with Flow Systems: Biological Applications and New Approaches" in IEEE Trans. on Nuclear Science, NS-21, pp 714-720 (1973) describe devices where the suspension stream is charged by suitable equipment shortly before the break-off of the droplet containing the particle after detecting the desired characteristic within an optic electronic system. A very strong electrostatic field of several thousand volts per centimeter, breaks up the flow of particle containing droplets into two or more streams depending on the polarity and charge of the droplets, and the various divided streams are collected in different small containers. Particle sorters of the type relying upon electrostatic separation of particles are described in U.S. Pat. Nos. 3,380,584; 3,710,933; 3,826,364; 4,148,718; 4,230,558; and 4,138,480.
The particle sorters which rely upon an electrostatic field for separating and sorting particles have particles charged with the same electrical polarity accumulate in respective collection wells. The result is that the collection well itself assumes the electrical polarity of the particles being collected. Once this electrical charge of the collection well is established, incoming particles of the same polarity are deflected because of the electrostatic force operating to separate charges of like nature. Removing the charge by a ground wire in the collection vessel is known. These sorters may produce aerosols which must be contained to avoid biological hazards to nearby personnel when sorting pathogenic particles.
U.S. Pat. No. 4,175,662 includes a method and apparatus for sorting of particles or cells in accordance with their physical or chemical properties where sorting is achieved after the particles are analyzed by reliance upon an electrolysis gas pressure impulse which causes a deflection of the particle suspension stream and flow into a different channel. This sorter may cause disturbances to the particle flow thru the laser beam thus interfering with the optical analysis of the particles.
An easily adapted sorter which does not rely on the deflection of the particles is required in order to minimize movement of, eliminate contact with, and prevent damage to the particles. With the foregoing in mind, improved techniques for sorting particles in a flow cytometer sample are still being sought. Such improvements in the simplification of sorting hardware and the adaptation and application of such hardware to a flow cytometer or other particle analyzer are needed. An improvement related to avoidance of biologically hazardous aerosols and to avoidance of pressure pulses which can disturb the optical alignment of the analysis apparatus is needed. It is toward such an improvement that the present invention is directed .